Commit 406b426 (Fix gravity) causes a weird issue for xfrun4, where the window width gets reset to 256 on every execution. The following screen capture shows the issue: https://dev.archlinux.org/~foutrelis/xfwm4-4.12.1-xfrun4-width-reset.mp4 I'm not sure if this a bug in xfwm4 or xfce4-appfinder though.
Oh crap you're right... 4.12.2 to come out soon :)
Fixed in git master and 4.12